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I am trying to rotate the NSImage around the vertical axis, saving the result. The main purpose is to generate an array of frames of the same image with different rotation degrees. I need to have that array to modify each frame separately. The desired result for a single frame is the following:

https://i.stack.imgur.com/wDy3p.jpg

So far I was trying to use CATransform3DRotate to make a single rotated NSImage, but I am not able to apply this transform to NSImage in any way. I tried applying CATransform3DRotate to a newly created CALayer and even to a layer of a specially created view, the best I can get is the same picture, as before.

CATransform3D t = CATransform3DRotate(CATransform3DIdentity, (60 * M_PI / 180), 0, 1, 0);
CALayer *layer = [CALayer layer];
[layer setFrame: imageRect];
[layer setContents:image];
[layer setTransform:t];
NSImage * newImage = [[NSImage alloc] initWithSize:layer.bounds.size];
[newImage lockFocus];
[layer renderInContext:[NSGraphicsContext currentContext].CGContext];
[newImage unlockFocus];

This code results in newImage being the same non-rotated image. I tried some other ways too, but none of them succeed.

Maybe there is an easier way to achieve my aim (generate the array of rotation frames of the same NSImage), but I have no idea, what it is.

Deimos
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1 Answers1

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NSImage object cannot be rotated. You need to rotate a view or layer and then save the contents of the view/layer as an image.

See Saving an NSView to a png file? for how to save a view as image.

cekisakurek
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  • That is exactly what I am trying to do. The code I posted is my attempt to rotate CALayer and save it back to NSImage. The main problem is that the result image is not rotated and I don't understand why. – Deimos Jun 27 '17 at 13:35